1. Field of the Invention
The present invention relates to an erasing device for use in a recording/reproducing apparatus.
2. Related Background Art
Various image recording/reproducing apparatus, such as video tape recorders and electronic still cameras have rapidly become popular in recent years. These apparatus are required to be small and compact and to be capable of battery operation because they are often used outdoors.
Such recording/reproducing apparatus basically have a recording mode, a reproducing mode and an erasing mode for erasing an unnecessary recorded signal. Since such modes are different in electric power consumption, it is desirable to monitor the output of the electric power supply in advance and to prohibit a mode if the power supply voltage required for said mode is not available, in order to prevent power supply deficiency in the course of an operation. Consequently, in the conventional recording/reproducing apparatus there is customarily defined a power source voltage for prohibiting the operation (hereinafter called limit voltage) for each operating mode.
However, in the conventional apparatus there is only defined a single limit voltage for each of the recording, reproducing and erasing modes. Consequently, even if the power source voltage is above the corresponding limit voltage at the start of an operation, it may become lower than the limit voltage in the course of operation, thereby resulting in a defective or erroneous operation. For example, certain electronic still cameras are provided, in addition to a single erasing mode for erasing the signal of individual track of the magnetic disk constituting the recording medium, with an all-track erasing mode for erasing all the tracks of the magnetic disk and/or a designated range erasing mode for erasing all the tracks in a designated range.
In such case, if a same limit voltage, for example enough for erasing all the tracks, is used for all the erasing modes, the erasing of a single track can only be achieved with the battery immediately after charging or immediately after the start of use.